Ground based radars often work in harsh environments where rain, snow, and contaminates in the form of dirt, dust, chemical and biological agents degrade and disable performance. Other disabling forces may come in the form of radiation from nuclear and electronic countermeasures. Typically the radar components are housed in enclosures. However, in addition to maintaining a shield against these potentially disabling forces and events, the enclosures themselves must withstand the deleterious effects of contamination such as water or corrosive decontamination fluids.
Radar antennas are usually mounted on the front end of a radar system, where the effects of these disabling events or forces may be especially severe. In the front or forward position the electronic and mechanical assemblies, assembly housings and associated small openings and joints collect dirt, sand and other debris. Additionally, mounting antenna elements requires holes to be cut in the front surface of enclosures, which after mounting are sealed against the weather and contamination. If a seal fails, contaminates such as water, sand, dirt, debris or corrosive fluids may enter the enclosure and damage the electronics or mechanical assemblies.
FIG. 1, FIG. 2a and FIG. 2b illustrate the prior art wherein a phased array antenna system 5 is comprised of a number of antenna elements 30 arranged in rows and/or columns 35. When the individual elements 30 are installed in the array 35, the joints 22 (shown as seams in FIG. 2b) between them may collect debris as mentioned above. The prior art shown in FIG. 1 and FIG. 2a illustrates the use of a patch element 30 consisting of alternating layers 24 of a generally foam material having two conductive sheets 23, 26. Sheet 26 forms the electrical feed patch, typically formed of copper or other conductive material that connects the antenna to the radar processing system. Sheet 23 is separated from the sheet 26 by the layers 24 to form a parasitic patch typically comprised of an aluminum or copper material to improve overall antenna performance. A reliable means for sealing the front surface of the antenna array 5 from harsh environments is needed to prevent damage or failure of the radar system.